The invention relates to the field of optics, and in particular to the creation of reflecting dielectric mirror structures, such as fibers.
Polymer fibers have become ubiquitous in applications such as textile fabrics, due to their excellent mechanical properties and availability of low-cost, high-volume processing techniques. However, the control over their optical properties has so far remained relatively limited. Conversely, dielectric mirrors are used to precisely control and manipulate light in high performance optical applications, but fabrication of these fragile mirrors has been mostly restricted to planar geometries and remains costly. Planar dielectric mirrors, also known as one-dimensional photonic crystals, can exhibit highly efficient reflection of electromagnetic (EM) radiation and precise frequency selectivity. Advances in vapor deposition technology have enabled a high degree of control over film layer thicknesses, resulting in an ability to control the spectral systems, laser resonator components, or simple high efficiency reflectors. Unlike metallic mirrors, which typically absorb a few percent of any incident light, dielectric mirrors can be fabricated with external reflectivities approaching 100%.
A typical dielectric mirror is a planar stack of dielectrics made of two alternating materials with different refractive indices. Although these mirrors do not possess a complete photonic band gap, it has recently been shown that they can be designed to reflect light of all incidence angles and polarizations across broad, selectable frequency ranges. This advance has inspired interest in the utilization of omnidirectional dielectric mirrors in applications requiring strong confinement or reflection of light at many angles, such as optical cavities or hollow waveguides.
The degree of utilization of all types of dielectric mirrors has been impeded by cost and complexity associated with their fabrication, which typically involves physical or chemical vapor deposition of many alternating layers in sequence, and by difficulties associated with depositing these mirrors on non-planar surfaces. In addition, the mirror films are typically fragile and not freestanding.